What was found
FLIGHT CREW NOTICED A LT ROLLING MOTION AFTER SLAT EXTENSION ALONG WITH A SLAT DISAGREEMENT LIGHT. COMPLIED WITH COM PROCEDURES AND NORMAL HYDRAULIC PRESSURE OF 3000 PSI WAS CONFIRMED. CAPTAIN DECLARED AN EMERGENCY WITH ATC, HAD CFR CALLED OUT, AND ACCOMPLISHED A 40 DEGREE FLAP AND NO SLAT LANDING AT ATL WITHOUT INCIDENT. MAINTENANCE FOUND A (T) DUCT CHATTERING AND LUBRICATED ALL (T) DUCTS ON THE AIRCRAFT. AIRCRAFT RETURNED TO SERVICE.